Specialized mass spectrometry analyses are provided to the laboratory and to other collaborating units. The emphasis of this work is split between identification of trace organic compounds isolated from biological sources and the mass spectrometry of biopolymers (e.g. peptides, proteins and oligonuceotides). A very close working relationship and collaboration is maintained with the Laboratory of Biophysical Chemistry, NHLBI, especially with the research into, and use of techniques for, mass spectrometry of macromolecules. The camera added to the electrospray source on the JEOL SX102 instrument allows for easy optimization of the spray during analyses. A request has been placed to upgrade the electrospray source to enhance stability and sensitivity, and to facilitate interfacing to liquid chromatographic methods. This will be used as part of the Unit's effort into post-translational modifications of proteins. The capillary zone electrophoresis instrument continues to receive heavy usage from this laboratory and others in the Institute. Its separation efficiency far surpasses that of traditional HPLC methods. As part of the macromolecule collaboration with LBC, NHLBI (Dr. Fales), routine use is made of a mass spectrometer especially set up for sequencing of protein digests. In addition, use is made of their laser desorption mass spectrometer for the analysis of proteins and protein digests as part of our work in biopolymer mass spectrometry. In the small molecule area, collaborative interest has continued in the identification of biologically active natural products, especially those of interest in AIDS research and treatment. Samples analyzed derive from many facilities and researchers and approximately 2800 samples were analyzed on the JEOL alone during the year.